Bottom Line:
Although human bodies can be found by smart vehicles and drones equipped with cameras, it is difficult to verify if the person is alive or dead this way.Finally, the detection capabilities of the radar system and the signal processing method are verified through experiments which show that human respiration signals can be extracted when the subject is 7 m away outdoors.The method provided in this paper will be a promising way to search for human subjects outdoors.

ABSTRACTAfter chemical or nuclear leakage or explosions, finding survivors is a huge challenge. Although human bodies can be found by smart vehicles and drones equipped with cameras, it is difficult to verify if the person is alive or dead this way. This paper describes a continuous wave radar sensor for remotely sensing the vital signs of human subjects. Firstly, a compact and portable 24 GHz Doppler radar system is designed to conduct non-contact detection of respiration signal. Secondly, in order to improve the quality of the respiration signals, the self-correlation and adaptive line enhancer (ALE) methods are proposed to minimize the interferences of any moving objects around the human subject. Finally, the detection capabilities of the radar system and the signal processing method are verified through experiments which show that human respiration signals can be extracted when the subject is 7 m away outdoors. The method provided in this paper will be a promising way to search for human subjects outdoors.

Mentions:
The largest difference between respiration signal and noise is periodicity. At present, there are many methods of extracting periodic signal from noise, such as self-correlation, adaptive line enhancer (ALE) [15], blind source separation (BBS) [16], empirical mode decomposition (EMD) [17], etc., nonetheless, the effect is not obvious when only using one of the methods mentioned above. Through research and comparison among these methods, this paper adopts a series of signal processing methods, as shown in Figure 2. Firstly, the radar signal is preprocessed to remove the baseline and background clutter, so as to improve the SNR of respiration signals. Secondly, self-correlation is adopted to improve the respiration signal and reduce colored Gaussian noise signals. Lastly, the ALE method is used for even reducing the Gaussian noise signal of the detected respiration.

Mentions:
The largest difference between respiration signal and noise is periodicity. At present, there are many methods of extracting periodic signal from noise, such as self-correlation, adaptive line enhancer (ALE) [15], blind source separation (BBS) [16], empirical mode decomposition (EMD) [17], etc., nonetheless, the effect is not obvious when only using one of the methods mentioned above. Through research and comparison among these methods, this paper adopts a series of signal processing methods, as shown in Figure 2. Firstly, the radar signal is preprocessed to remove the baseline and background clutter, so as to improve the SNR of respiration signals. Secondly, self-correlation is adopted to improve the respiration signal and reduce colored Gaussian noise signals. Lastly, the ALE method is used for even reducing the Gaussian noise signal of the detected respiration.

Bottom Line:
Although human bodies can be found by smart vehicles and drones equipped with cameras, it is difficult to verify if the person is alive or dead this way.Finally, the detection capabilities of the radar system and the signal processing method are verified through experiments which show that human respiration signals can be extracted when the subject is 7 m away outdoors.The method provided in this paper will be a promising way to search for human subjects outdoors.

ABSTRACTAfter chemical or nuclear leakage or explosions, finding survivors is a huge challenge. Although human bodies can be found by smart vehicles and drones equipped with cameras, it is difficult to verify if the person is alive or dead this way. This paper describes a continuous wave radar sensor for remotely sensing the vital signs of human subjects. Firstly, a compact and portable 24 GHz Doppler radar system is designed to conduct non-contact detection of respiration signal. Secondly, in order to improve the quality of the respiration signals, the self-correlation and adaptive line enhancer (ALE) methods are proposed to minimize the interferences of any moving objects around the human subject. Finally, the detection capabilities of the radar system and the signal processing method are verified through experiments which show that human respiration signals can be extracted when the subject is 7 m away outdoors. The method provided in this paper will be a promising way to search for human subjects outdoors.